♻️(models) rename document/template access rights

The "member" access right does not make sense for documents and templates.
What we really need are "editor" and "reader" access rights.

src/backend/core/admin.py

@@ -91,7 +91,7 @@ class DocumentAdmin(admin.ModelAdmin):
     """Document admin interface declaration."""
 
     inlines = (DocumentAccessInline,)
-    
+
 
 @admin.register(models.Invitation)
 class InvitationAdmin(admin.ModelAdmin):
@@ -119,4 +119,3 @@ class InvitationAdmin(admin.ModelAdmin):
     def save_model(self, request, obj, form, change):
         obj.issuer = request.user
         obj.save()
-